Castable refractory composition

Abstract

A castable refractory composition may include from 5% to 95% by weight of alumina, aluminosilicate, or mixtures thereof; up to 70% by weight silicon carbide; up to 10% by weight carbon; from 0.1% to 5% by weight alkaline earth metal oxide and/or hydroxide; and from 0.1% to 5% by weight of silica having a surface area of at least about 10 m 2 /g. The refractory composition may further include no more than 0.5% by weight of cementitious binder, and the refractory composition may not release a significant amount of hydrogen gas upon addition of water. The refractory composition may set on addition of water. An installable refractory lining may be formed using the composition and a method including at least one of casting, self-flowing, wet shotcreeting, rodding, cast-vibrating, spraying, conventional dry gunning, or high density gunning the castable refractory composition, and setting and drying the composition.

The invention claimed is: 
     
       1. A castable refractory composition comprising:
 from 5% to 95% by weight of alumina, aluminosilicate, or mixtures thereof; 
 silicon carbide in an amount up to 70% by weight; 
 carbon in an amount up to 10% by weight; 
 from 0.1% to 5% by weight alkaline earth metal oxide and/or hydroxide; and 
 from 0.1% to 5% by weight of silica having a surface area of at least about 10 m 2 /g, 
 wherein the refractory composition comprises no more than 0.5% by weight of cementitious binder, 
 wherein the refractory composition releases less than 25 cm 3  of hydrogen gas per kilogram of wetted castable refractory composition, and 
 wherein the refractory compositions sets on addition of water. 
 
     
     
       2. A castable refractory composition according to  claim 1 , further comprising up to about 1% by weight of metallic additives. 
     
     
       3. A castable refractory composition according to  claim 1 , further comprising up to about 5% by weight of an additive or combination of additives, which suppress or prevent the oxidation of carbon. 
     
     
       4. A castable refractory composition according to  claim 1 , further comprising up to 0.5% by weight of organic fibers. 
     
     
       5. A castable refractory composition according to  claim 1 , wherein the alumina, aluminosilicate or mixtures thereof comprise a material selected from the group consisting of brown fused alumina, sintered alumina, white fused alumina, calcined alumina, reactive or semi-reactive alumina, bauxite, fused or sintered mullite, andalusite and calcined chamotte with alumina content ranging from 30 to 75% by weight. 
     
     
       6. A castable refractory composition according to  claim 1 , comprising from 5% to 70% by weight silicon carbide and/or from 1% to 10% by weight carbon. 
     
     
       7. A castable refractory composition according to  claim 1 , wherein the silicon carbide comprises particles up to about 30 mm in size. 
     
     
       8. A castable refractory composition according to  claim 1 , wherein the carbon comprises a material selected from carbon black, graphite, coke, solid hydrocarbon having a carbon residue of at least about 5% by weight after coking, or a combination thereof. 
     
     
       9. A castable refractory composition according to  claim 1 , wherein the silica having a surface of at least about 10 m 2 /g is selected from the group consisting of fumed silica, silica fume, microsilica, micro grinded silica, and precipitated silica. 
     
     
       10. A castable refractory composition according to  claim 1 , wherein the alkaline earth metal oxide and/or hydroxide is an oxide and/or hydroxide of magnesium, calcium, barium, or mixtures thereof. 
     
     
       11. A castable refractory composition according to  claim 1 , wherein the composition comprise less than about 0.5% by weight calcium aluminate cement and/or calcium silicate cement. 
     
     
       12. An installable refractory lining obtained by mixing the castable refractory composition according to  claim 1  with from 2% to 40% by weight water. 
     
     
       13. A method of installing the installable refractory lining of  claim 12 , the method comprising at least one of casting, self-flowing, wet shotcreeting, rodding, cast-vibrating, spraying, conventional dry gunning, or high density gunning the castable refractory composition; and setting and drying the castable refractory composition to form the refractory lining. 
     
     
       14. The method of  claim 13 , wherein the setting comprises reaction of the alkaline earth metal oxide and/or hydroxide, silica having a surface area of at least 10 m 2 /g, and water, without firing the castable refractory composition. 
     
     
       15. The method of  claim 14 , wherein the mixture releases less than 10 cm 3  of hydrogen gas per kilogram of wet castable refractory. 
     
     
       16. An installed factory lining obtained by the method of  claim 13 . 
     
     
       17. A method of installing a refractory comprising:
 mixing the castable refractory composition according to  claim 1  with water; 
 forming the mixture into an article; 
 allowing the article to set; and 
 drying the article to remove excess water. 
 
     
     
       18. The method of  claim 17 , further comprising firing the article. 
     
     
       19. A refractory article obtained by the method of  claim 17 . 
     
     
       20. The castable refractory compound of  claim 1 , comprising silicon carbide in an amount between 15-40% by weight.